Traditionally, the number of phases cannot be made as large in a reluctance-type motor as in a typical commutator motor. This is because practicability is lost since the cost of the semiconductor circuit of each phase is high.
Accordingly, the stored magnetic energy of each magnetic pole becomes large and it takes time to discharge and store. Thus there is a problem that the torque becomes high but the speed does not.
Further, particularly in a reluctance-type motor having a large output torque, the number of magnetic poles of the armature becomes large and the air-gap of the magnetic path thereof is small, so that the stored magnetic energy is large, whereby the above-mentioned inconvenience is accelerated.
The higher the torque, the more impossible the solution to this problem.
Next, because of the large inductance of armature coils, there is a problem that the rise and fall times of the armature current increase thereby making the ripple of the output torque large.
Moreover, there is a problem that an efficiency is also degraded.
Accordingly, it is the object of this invention to provide a reluctance-type motor which is high-speed, highly efficient, small-sized and inexpensive.